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Research and Development Laboratories 

of the 
Portland Cement Association 



RESEARCH DEPARTMENT 

Bulletin 82 



Curing Requirements for Scale 

Resistance of Concrete 



By 
Paul Klieger 



June, 1957 
Chicago 



Authorized Reprint from 

Highway Research Board Bulletin No. 150 

January, 1956 



Curing Requirements for Scale 

Resistance of Concrete 



t 



By 
Paul Klieger 



Curing Requirements for Scale Resistance 
Of Concrete 

PAUL KLIEGER, Senior Research Engineer, Applied Research Section 
Research and Development Division, Portland Cement Association 

The record of field performance of air -entrained concrete pavement with 
regard to surface scaling resulting from the use of de-icers is excellent. 
Approximately 15 years of field experience, together with extensive labor- 
atory tests, have shown that the use of entrained air has solved an impor- 
tant pavement problem which was becoming more serious with the increas- 
ing use of chemicals for ice control. 

The problem of the earliest age at which de-icers, such as calcium 
chloride, may safely be used on new air-entrained concrete pavements is 
of concern to highway engineers. This concern stems from previous prac- 
tical experience with non-air-entrained concrete pavements- Shortly after 
the introduction of the use of de-icers, field surveys indicated that older 
non-air-entrained pavements resisted surface scaling better than relatively 
new non-air-entrained pavements. This led to the establishment of mini- 
mum ages at which de-icers might safely be used; however, the various 
highway departments were far from agreement on these age requirements, 
A recent survey of highway department practices, conducted by Committee 
B-7 of the Highway Research Board, indicates that these minimum ages 
ranged from a few months up to 5 and 10 years. Despite the excellent per- 
formance record of air-entrained concrete pavements, many states are 
applying the same age requirements to both types of concrete pavement. 

Only a limited amount of information is available bearing directly on 
this problem (1). This study was undertaken, therefore, to provide addi- 
tional information which might interest those concerned with the use of de- 
icers on new air-entrained concrete pavements. 

THE study consisted of laboratory surface scaling and strength tests of both non-air- 
entrained and air-entrained concretes. Types I, II, and III portland cements were used 
in preparing these concretes having essentially identical cement contents and slumps. 
Concretes with Type I and II cements were made both with and without calcium chloride 
added as an accelerator. Air entrainment was accomplished by adding an agent at the 
mixer. 

The concretes were fabricated at one temperature level (40 deg F) to simulate cold 
weather construction. Specimens were cured at three different temperature levels 
(73 deg F, 40 deg F, ana 25 deg F) for different periods of time before making strength 
determinations and testing for scale resistance. Curing periods prior to testing ranged 
from one day to 60 days, the selected intervals depending upon type of cement, pres- 
ence or absence of an accelerator, and temperature of curing. 

Materials 

The cements used in these tests, all meeting applicable ASTM requirements, were 
obtained from commercial sources. The Type I cement was a blend prepared from 
equal parts of four different brands, the Type n was an individual brand, and the Type 
III cement was a blend of equal parts of two different brands. Tables 1, 2, 3, and 4 
show the chemical compositions, calculated potential compound compositions, and the 
results of various physical tests of the cements and mortars made. 

The fine aggregate was a predominantly dolomitic natural sand from Elgin, Illinois. 
The coarse aggregate, a highly siliceous crushed gravel from Eau Claire, Wisconsin, 
was selected as representative of sound, durable coarse aggregates commonly used in 
concrete pavement construction. Grading, specific gravity, absorption, and thermal 
coefficient of linear expansion are shown in Table 5. 

18 




19 



TABLE 1 
CHEMICAL COMPOSITION OF CEMENTS 

Chemical analyses of cements made in accordance with ASTM method of test current in May, 1954 
Sodium oxide and potassium oxide by flame photometry, ASTM C228-49T. 



Cement 






Major 
Fe 2 3 


• Components ■ 

Total MgO 
CaO 


-% 

SO 3 


Ign 
Loss 


MnaOa 


Minor Components - % 




Si0 2 

21.44 
21.26 
19.77 


AbOs 

5.94 
5.08 
5.88 


Alkalies 


Lot ASTM 
No. Type 


Free Insol Na 2 K2O Tot. as 
CaO Res Na a O 


18868 I 
18914 II 

18893 IH 


2.67 
3. 72 
2. 61 


63. 10 2. 62 
61.61 3.77 

64. 77 1. 76 


2.05 
1.70 
2.83 


1. 07 
1. 61 
1.59 


0.26 
0.07 
0. 19 


0, 83 0. 18 0. 22 0. 66 0, 65 
0.86 0. 18 0.26 0.75 0.75 
1.55 0, 13 0. 16 0.46 0.46 



TABLE 2 
POTENTIAL COMPOUND COMPOSITION OF CEMENTS 
Corrected for free CaO 



Aggregates were air -dried and screened 
into various size fractions — six sizes for 
the fine aggregate and three for the coarse 
aggregate. When batching, the sizes were 
recombined to yield the gradings shown in 
Table 5. Aggregates were weighed in the 
air-dried condition (moisture content 
known) and, 18 to 20 hours prior to use, 
inundated with a known amount of water. 
Prior to mixing, excess water was drawn 
off and weighed to permit calculating the net water-cement ratios. 

Neutralized Vinsol resin in solution was added at the mixer when preparing the air- 
entrained concretes. Commercial flake calcium chloride was used both as the de-icer 
and the accelerator. 



Cement 


Calculated 
C,S C*S 


Compc 
CjA 


)unt Co 
C«AF 


mposition 


% 


Lot ASTM 
No. Type 


CaSOt 


Free 
CaO 


18866 I 
18914 II 
18893 ID 


40. 9 30. 6 
41.4 29.7 
55. 8 14. 8 


11. 2 

7.2 

11.1 


8. 1 

11.3 

7.9 


3.49 
2 89 
4. 81 


0.83 

0. 86 

1. 55 



TABLE 3 
MISCELLANEOUS PHYSICAL TESTS OF CEMENTS 

Tests made in accordance with ASTM methods of test current in May, 1954. 
Each value is the average of two or more determinations. 



Cement 



Fineness 



Lot 
No. 



ASTM Spec Surface 
Type sq cm per g 



18868 I 
18914 ll 

18893 in 



Wagner Blaine 



ing 
325 

Mesh 

% 



1630 
1710 
2520 



3230 
3275 

5120 



89.0 
90.0 
98.4 



Spe- 
cific 
Grav- 
ity 



3. 160 
3. 180 
3. 114 



Normal 
Consis- 
tency 



24.5 
23.0 

29,0 



Time of Setting 



Gil mo re 



Vicat 
h. m. 



Auto- 
— clave 
Initial Final Exp 
h. m. h. m. % 



3:35 
4: 20 
1:30 



4: 00 
5:25 
2: 00 



5: 35 0. 11 
7: 10 0. 13 

4: 20 0. 11 



Air 
Content 

% 
1-4 

Mortar 



9. 2 
9.3 
5.0 



TABLE 4 

STRENGTH TESTS OF MORTARS 

Briquets: ASTM C 190-49. Cubes: ASTM C 109 -52. 

Each value is the average of three specimens, each made on a different day. 



Cement 



Lot 

No. 

11868 
18914 
18893 



ASTM 
Type 



Tensile Strength, 1-3 Std Sand 
Mortar Briquets - psi 



Compressive Strength, 2-in. 
Plastic Mortar Cubes - psi 



Id 



3d 



7d 



28d 



Id 



3d 



7d 



28d 



I 


185 


325 


415 


485 


810 


1850 


3080 


4460 


B 


150 


240 


355 


450 


600 


1420 


2230 


4000 


in 


355 


425 


520 


545 


2110 


3720 


5200 


6400 



20 



TABLE 5 
DATA ON AGGREGATES 



Elgin, Illinois, Sand 



Grading - % Retained 
On Sieve No. Indicated 



Fineness 
Modulus 



8 16 30 



50 100 



Bulk 
Spec if ic 
Gravity 
S. S. D. a 



24-Hr 

Absorption 
%by Wt 



Mean Linear 

Thermal Coeff 

of Expansion 



18 33 57 



87 



95 



2.90 



2.645 



2.25 



5. 73x10 



-« 



Eau Claire, Wisconsin, Gravel 



Grading - % Retained 
On Sieve Size Indicated 



1-in 



3/ 

4-in. 



3 



%- 



in. 



No. 4 



Bulk 

Specific 
Gravity 

S. S. D. a 



24-Hr 

Absorption 

% by Wt 



Mean Linear 
Thermal Coeff 
of Expansion k 







25 



70 



100 



2.693 



1.33 



5. 94xl0" e 



b 



Saturated - surface dry 
Dilatometer method. 



Concrete Mix Data 

The concretes were designed to have a cement content of 6 sacks per cu yd and a 
slump of 2% to 3 l /a in. at 40 deg F. The maximum size of aggregate was 1 in. For 
the air-entrained concretes, the air content was maintained in the range of 5 t % per- 
cent the optimum amount for these concretes (2). Where calcium chloride was used as 
an accelerator. I was used in the amount of 2 percent by weight of the cement and dis- 
solved in a portion of the mixing water immediately before mixing. Table 6 shows the 
pertinent data for the concrete mixes used in this investigation. 

Fabrication of Specimens 

All materials were at a temperature of 40 deg F for 24 hours prior to mixing con- 
cretes. Mixing and fabricating operations were conducted in a laboratory maintained 
at 40 deg F, simulating temperature conditions likely to prevail during late fall paving. 

Eight batches were prepared for each type of concrete. Batches were mixed for 2% 
minutes in an open-tub mixer of 1%-cu-ft capacity. A slump test and an air content 
determination by the pressure method 
were made on 4 of the 8 like batches. 
Each batch contained sufficient concrete 
for 4 scale test specimens and four 6- by 
12-in. cylinders, making a total of 32 
slabs and 32 cylinders per type of con- 
crete. 

The scale test specimens were slabs 
3 in. in depth and 6 by 15 in in area. 
These slabs were cast in watertight steel 
molds, the molds were filled in two lay- 
ers of equal depth, and each layer was 
rodded 50 times with a 5 /i-in. diameter 
bullet-nose tamper. Immediately after 
casting, the surface was given a final fin- 
ish with a wood float. Approximately 
three hours after casting, the slabs were 
equipped with a 1: 2 air-entrained mortar 
dike around the edges of the finished sur- 
face. 



TABLE 6 
CONCRETE MM DATA 





Cement _ 5 ement 


Air 
f lent 

1 

(Pressure) 


Ref 
No. 


Lot 

No. 


ASTM gal per Slump sacks per 
Type sack in cu yd 

No CaClt - Non-Air-Entrained 


1 

14 

3 


16668 
16914 
18691 


I 4.63 3 3 6.00 
U 4 63 2.8 6.02 
IH 5.62 3.2 5.96 


I. 60 

1 70 
1 . 60 




2% CaCU - Non-Air-Entrained 




4 
15 


18666 
18914 


I 4.79 2.6 5,96 

II 1 56 2. 5 5. 93 


1 90 

I 85 




No CaCl» - Air-Entrained a 




: 

16 
9 


6666 

18914 
16893 


I 4.45 2.9 5.98 
U 4.37 2.8 5.96 
III 5. 34 3. 7 5. 98 

2* CaCU - Air-Entrained* 


4 70 

5 30 
5. 10 


10 
17 


18868 
18914 


1 4 32 2.5 5.96 
n 4.25 2.6 5.95 


4 60 

4.90 


a Neutralized Vtnsol resin in solution added at m 


uer. 



21 



TABLE 7 
RESULTS OF SURFACE SCALING AND STRENGTH TESTS - TYPE I CEMENT 

Type I Cement - Lot 18868. No CaCl a . 

Cement content of all concretes - 6 sacks per cu yd. 

Neutralized Vinsol resin added at mixer for air-entrained concrete. 

All specimens cured continuously moist for times indicated. 

Net W/C: Non-A/E concrete - 4. 8 gal per sack. A/E concrete - 4. 5 gal. per sack. 

Air content (pressure): Non-A/E - 1. 60%. A/E - 4. 70% 



Compressive 
Days Curing Strength 

of Temp psi 

Curing F 6- xl2-in. Cyl 



Scale Ratings at Indicated Number of Cycles 



5 



10 



15 25 50 75 100 150 200 250 











Non- Air -Entrained 


1 

3 

28 


73 
73 
73 


960 
2700 
6270 


2 

1- 




3 4+ (16) a 

2+ (15) 

0+3 (50) 



2 


40 


330 


2 


3 


(15) 
















4 


40 


1120 


3+ 


4+ 


(13) 
















6 


40 


1940 


1+ 


3+ 


4+ 


(16) 














8 


40 


2960 


1 


3+ 


(15) 
















12 


40 


4020 


1 


3 


4+ 


(17) 














19 


40 


4880 


1+ 


3 


4+ 


(19) 














30 


40 


5540 


1 


4- 


5- 


(16) 














60 


40 


6410 


0+ 


3+ 


4+ 


(23) 














9 


25 


440 


0+ 


2 


(15) 
















18 


25 


560 


0+ 


1 


2 


(16) 














28 


25 


560 


0+ 


(10) 


















40 


25 


520 


1- 


1+ 


3 


(17) 














60 


25 


680 


0+ 


1+ 


(15) 
























Air- Entrained 














1 


73 


1050 


1+ 


2 


2 


2+ 


3+ 


4- 


(95) 








3 


73 


2720 











0+ 


1- 


1 


1+ 


2- 


2- 


2- 


28 


73 


5500 











0+ 


0+ 


0+ 


0+ 


0+ 


0+ 


0+ 


2 


40 


420 


3- 


3+ 


4- 


4+ 


(35) 












4 


40 


1060 


2- 


2 


3+ 


4- 


(40) 












6 


40 


1780 


0+ 


0+ 


1- 


1- 


3- 


3 


3+ 


5- 


5- 


5- 


8 


40 


2730 





0+ 


0+ 


1- 


1+ 


2 


2+ 


4+ 


5- 


5- 


12 


40 


3460 





0+ 


0+ 


1- 


1+ 


2- 


2- 


2+ 


3+ 


4- 


19 


40 


4360 











0+ 


0+ 


0+ 


0+ 


1- 


1+ 


2 


30 


40 


4900 











0+ 


0+ 


0+ 


0+ 


1- 


1 


1+ 


60 


40 


5680 


0+ 


0+ 


0+ 


0+ 


0+ 


0+ 


0+ 


0+ 


1- 


1- 


9 


25 


540 


0+ 


1- 


2+ 


3+ 


(31) 












18 


25 


720 


0+ 


1- 


1 


(22) 














28 


25 


900 








0+ 


0+ 


1- 


1 


1+ 


(106) 






40 


25 


1030 





1- 


1- 


1- 


1- 


1- 


1 


3 


3 


(220) 


60 


25 


1010 


0+ 


1- 


1- 


1- 


1 


1+ 


1+ 


2 


(167) 





( ) - Number of cycles at which test was discontinued at a rating of 5 



22 



8 



TYPE 



Type I Cement - Lot 18868 plus 2% CaCl 2 , by weight of cement. 

Cement content of all concretes - 6 sacks per cu yd. 

Neutralized Vinsol resin added at mixer for air-entrained concrete. 

All specimens cured continuously moist for times indicated. 

Net W/C: Non-A/E concrete - 4. 8 gal. per sack. A/E concrete - 4. 3 gal. per sack 

Air content (pressure): Non-A/E - 1. 90%. A/E - 4. 80%. 







Compressive 






















Days 
of 


Curing 
Temp 


Strength 
psi 




Scale Ratings at Indicated Number of Cycles 




Curing 


F 


6- x 12-in. Cyl 


5 


10 


15 


25 


50 


75 


100 


150 


200 


250 






Non-A 


ir-Ent] 


rained 














1 


73 


2260 


3 


4+ 


(H) a 
















3 


73 


3940 





0+ 


2 


5- 


(27) 












28 


73 


6460 








0+ 


1 


3- 


(60) 










1 


40 


350 


(5) 




















2 


40 


1290 


5- 


(6) 


















3 


40 


2340 


2+ 


(9) 


















4 


40 


2940 


2+ 


4+ 


(13) 
















7 


40 


4120 


2- 


3+ 


4+ 


(17) 














12 


40 


4970 


1- 


2 


4 


(21) 














30 


40 


5820 


1- 


2- 


3- 


(22) 














60 


40 


6560 











0+ 


2 


(55) 










2 


25 


640 


4+ 


(6) 


















5 


25 


1670 


3- 


4+ 


(12) 
















10 


25 


2840 


2- 


3 


5- 


(16) 














30 


25 


3960 


1- 


1- 


2- 


2+ 


(36) 












60 


25 


3960 


1+ 


2- 


3- 


3+ 


(36) 


















0+ 


Air-Entrained 














1 


73 


2020 


1 


1 + 


2- 


3+ 


4- 


4 


4+ 


4+ 


5- 


3 


73 


3450 











0+ 


1- 


1- 


1+ 


2 


2+ 


2+ 


28 


73 
40 


5330 











0+ 


0+ 


0+ 


0+ 


0+ 


0+ 


0+ 


1 


340 


(3) 
















2 


40 


1340 


3+ 


4+ 


4+ 


(19) 














3 


40 


2000 


2- 


3 


3+ 


4- 


(34) 












4 


40 


2540 


0+ 


1- 


1+ 


2- 


2+ 


3- 


3 


3+ 


4- 


4 


7 


40 


3670 














0+ 


0+ 


0+ 


0+ 


0+ 


1- 


12 


40 


4530 














0+ 


0+ 


0+ 


1- 


(190) 




30 


40 


5170 




















0+ 


0+ 


0+ 


0+ 


60 


40 
25 


5580 























0+ 


0+ 


0+ 


2 


340 


2+ 


3+ 


4+ 


(19) 














5 


25 


980 


2 


3+ 


4+ 


(25) 














10 


25 


1480 


1- 


3+ 


4- 


4+ 


(28) 












30 


25 


2270 


0+ 


1 


1 


1 


1 


1 


1 


1 


1 


1 


60 


25 


2520 













;inued 


0+ 

at a \ 


0+ 0+ 
rating of 5. 


0+ 

i 


0+ 


0+ 


a ( ) - Number < 


of cycles at which test was 


discont 





23 



TABLE 9 

RESULTS OF SURFACE SCALING AND STRENGTH TESTS - TYPE II CEMENT 

Type II Cement - Lot 18914. No CaCl 2 . 

Cement content of all concretes - 6 sacks per cu yd. 

Nautralized Vinsol resin added at mixer for air-entrained concrete. 

All specimens cured continuously moist for times indicated. 

Net W/C: Non-A/E concrete -4. 6 gal. per sack. A/E concrete - 4. 4 gal. per sack. 

Air content (pressure): Non-A/E - 1. 70%. A/E - 5. 30%. 



1 

7 

28 



3 
7 
12 
20 
30 
40 
50 
60 



8 
20 

35 
45 
60 



73 
73 
73 



40 
40 
40 
40 
40 
40 
40 
40 



25 
25 
25 
25 
25 







Compressive 
















Days 
of 


Curing 
Temp 


Strength 
psi 






Scale 


Ratings at Indicated Number of Cycles 


Curing 


F 


6- xl2-in. 


Cyl 


5 


10 


15 


25 
lined 


50 


75 


100 150 200 250 




Nc 


m-Air 
3 


-Entrs 
(14)* 




i 


73 


780 




0+ 










7 


73 


3860 




0+ 


1 


2- 


(22) 








28 


73 
40 


6300 
880 




0+ 

1- 


1- 
3 


1+ 
(15) 


2 


3- 


3+ 


(83) 


3 




7 


40 


2560 




0+ 


2- 


2+ 


(20) 








12 


40 


3660 




0+ 


0+ 


2+ 


(22) 








20 


40 


4780 




0+ 


0+ 


2+ 


(25) 








30 


40 


5220 




0+ 


0+ 


1- 


2 


(39) 






40 


40 


5990 




0+ 


0+ 


1- 


2 


(38) 






50 


40 


6060 




0+ 


0+ 


1- 


1- 


3 






60 


40 


6060 




0+ 


0+ 


1- 


2+ 


(50) 


— 




8 


25 


560 




0+ 


1+ 


(15) 






20 


25 


900 




0+ 


1- 


1+ 


(25) 








35 


25 


1180 




0+ 


1- 


1 


2- 


(29) 






45 


25 


1480 




0+ 


1- 


1 


2- 


(32) 






60 


25 


1490 




0+ 


1- 


1 


1+ 


(50) 














A 


ir-Entrained 


I 









650 
3250 
5520 



0+ 







1 

0+ 



1+ 


0+ 



2+ 

0+ 
0+ 



3 3 3+ 
0+ 0+ 0+ 
0+ 0+ 1- 



3+ 

0+ 

1- 



3+ 
0+ 
1- 



3+ 
0+ 
1- 



880 
2280 
3420 
4280 
4360 
5010 
5360 
5120 



500 

750 

880 

1070 

1240 



1- 


3 


4 


4+ 


(42) 













0+ 


0+ 


0+ 


1- 


1- 


1 1 


1+ 


1 + 








0+ 


0+ 


0+ 


0+ 


0+ 1- 


1 — 


1 — 








0+ 


0+ 


0+ 


0+ 


0+ 1- 


X — 


\ — 








0+ 


0+ 


0+ 


0+ 


0+ 1- 


1- 


1 — 


0+ 


0+ 


0+ 


0+ 


0+ 


1- 


1- 1 






0+ 


0+ 


0+ 


0+ 


0+ 


1 — 


1- 1- 


X — 




0+ 


0+ 


0+ 


0+ 


1- 




1 1 









0+ 


0+ 


1- 


1 


1+ 


2- 2- 


2 (: 


L90) 


0+ 


0+ 


0+ 


1- 


1- 




1 1+ 


1+ I 


1+ 





0+ 


1- 


1- 


1- 


1 — 


1- 1- 


1 " 4 


L - 





0+ 


0+ 


1- 


1- 


1- 


1- 1- 


1- ] 


L - 


0+ 


0+ 


1- 


1- 


1- 


[» 


1- 1- 


1 — 


i — 



( ) - Number of cycles at which test was discontinued at a rating of 5. 



24 



TABLE 10 
RESULTS OF SURFACE SCALING AND STRENGTH TESTS - TYPE II CEMENT 

Type II Cement - Lot 18914 plus 2% CaCh, by weight of cement. 

Cement content of all concretes - 6 sacks per cu yd. 

Neutralized Vinsol resin added at mixer for air-entrained concrete. 

All specimens cured continuously moist for times indicated. 

Net W/C: Non-A/E concrete - 4. 6 gal. per sack. A/E concrete - 4. 3 gal. per sack. 

Air content (pressure): Non-A/E - 1. 85%. A/E - 4. 90%. 







Compressive 




















Days 
of 


Curing 
Temp 


Strength 
psi 




Scale Ratings at Indicated Numbe 


r of 


Cycles 




Curing 


F 


6- xl2-in. Cyl 


5 


10 


15 


25 


50 


75 100 


150 


200 


250 








Non-Air- 


-Entra 


ined 












1 


73 


1640 


2+ 


(10) a 
















7 


73 


4590 








0+ 


A- 


(36) 










28 


73 


6180 





0+ 


0+ 


1- 


2- 


(69) 








1 


40 


260 


3+ 


(7) 
















2 


40 


930 


3+ 


(9) 
















5 


40 


2820 


3+ 


(10) 
















7 


40 


3680 


1- 


2+ 


3 


(21) 












12 


40 


4620 








0+ 


1- 


(47) 










20 


40 


5630 








0+ 


1- 


(42) 










30 


40 


5980 











0+ 


(45) 










60 


40 


6950 











0+ 


(32) 










3 


25 


530 


4- 


(8) 














8 


25 


1890 


3 


4+ 


(12) 














16 


25 


3000 


1- 


2- 


4- 


4+ 


(32) 










32 


25 


4200 





0+ 


1- 


2+ 


3+ 


(70) 








60 


25 


4880 





0+ 


0+ 


1- 


3- 


(60) 














Air-Entrained 














1 


73 


1540 


2+ 


4- 


(13) 














7 


73 


4480 











0+ 


0+ 


0+ 0+ 


0+ 


1- 


1 


28 


73 


5720 














0+ 


0+ 0+ 


0+ 


0+ 


0+ 


1 


40 


250 


4 


(10) 
















2 


40 


1000 


4 


(10) 
















5 


40 


2820 


0+ 


1+ 


2- 


2+ 


3- 


3+ 3+ 


4- 


4+ 


4+ 


7 


40 


3300 





0+ 


1- 


1- 


1- 


1- 1- 


•1- 


1- 


1- 


12 


40 


4180 

















0+ 0+ 


0+ 


0+ 


0+ 


20 


40 


4800 


























0+ 


30 


40 


5140 





























60 


40 
25 


6020 
530 





























3 


3 


(10) 
















8 


25 


1500 


2- 


3+ 


4 


4+ 


(34) 










16 


25 


2580 





0+ 


1 


1+ 


2+ 


2+ 2+ 


2+ 


2+ 


3- 


32 


25 


3340 





0+ 


0+ 


0+ 


0+ 


0+ 0+ 


0+ 


0+ 


0+ 


60 


25 


4200 


0+ 
\h test 


0+ 


0+ 


0+ 


0+ 


0+ On- 


0+ 


0+ 


0+ 


a ( ) - 


Number 


of cycles at whic 


: was discontinued at a 


rating of 5 


1 







25 



TABLE 11 
RESULTS OF SURFACE SCALING AND STRENGTH TESTS - TYPE III CEMENT 

Type HI Cement - Lot 18893. No CaCb. 

Cement content of all concretes - 6 sacks per cu yd. 

Neutralized Vinsol resin added at mixer for air-entrained concrete. 

All specimens cured continuously moist for times indicated. 

Net W/C: Non-A/E concrete - 5. 6 gal. per sack. A/E concrete - 5. 

Air content (pressure): Non-A/E - 1. 60%. A/E - 5. 10%. 



3 gal. per sack. 



Days 
of 

Curing 



1 
3 
28 



Compressive 
Curing Strength 
Temp psi 

F 6- x 12-in. Cyl 



Scale Ratings at Indicated Number of Cycles 
10 15 25 50 75 100 150 200 250 



73 
73 
73 



1600 
3560 
5550 



Non- Air-Entrained 



2 

0+ 





2+ 

2+ 
0+ 



(13) a 
4+ (18) 
2- 3- (50) 



1 


40 


160 


2 


(10) 


















3 


40 


1480 


1 


(10) 


















5 


40 


2920 





4 


(15) 
















7 


40 


4280 


1- 


3+ 


(14) 
















9 


40 


4970 


0+ 


1+ 


4 


(19) 














12 


40 


5410 





1+ 


3+ 


(23) 














30 


40 


6370 





0+ 


1 


3- 


(40) 












60 


40 


6960 








0+ 


2 


(50) 












6 


25 


600 


1- 


2+ 


(15) 












13 


25 


1020 





1+ 


3+ 


(19) 














21 


25 


770 





0+ 


1+ 


(25) 














32 


25 


720 








0+ 


(25) 














60 


25 


720 








0+ 


1- 


(31) 
















Ai] 


r-Entrained 
















1 


73 


1400 


1- 


2- 


3- 


4+ 


5- 


(75) 










3 


73 


3020 











0+ 


0+ 


1- 


1+ 


3 


3+ 


4- 


28 


73 


4730 














0+ 


0+ 


0+ 


0+ 


1- 


1- 


1 


40 


100 


1+ 


3+ 


4+ 


(20) 










3 


40 


1350 


1 


2+ 


3+ 


4 


(40) 












5 


40 


2660 











0+ 


0+ 


1- 


1+ 


2- 


3 


4- 


7 


40 


3760 











0+ 


0+ 


0+ 


1- 


1+ 


2+ 


3+ 


9 


40 


4160 




















0+ 


0+ 


1- 


1- 


12 


40 


4920 




















0+ 


0+ 


1- 


1- 


30 


40 


6200 




















0+ 


0+ 


0+ 


0+ 


60 


40 


6310 









3+ 



4 



(30) 








0+ 


1- 


1- 


6 


25 


740 


0+ 


2+ 




13 


25 


1830 








0+ 


0+ 


1- 


2 


3 


5- 


5 


(175) 


21 


25 


2820 














0+ 


1- 


1+ 


2 


2+ 


3 


32 


25 


3440 

















0+ 


0+ 


0+ 


0+ 


0+ 


60 


25 


3260 

















0+ 


0+ 


0+ 


0+ 


0+ 



( ) - Number of cycles at which test was discontinued at a rating of 5. 



26 

The 6- by 12-in. cylinders were cast in watertight steel molds, the molds were filled 
in three layers of equal depth, and each layer was rodded 25 times with a %-iiL diam- 
eter tamping rod. 

Curing Conditions 

Immediately after casting, six companion slabs and cylinders for each type of con- 
crete were removed to a room maintained at 73 deg F; ten companion slabs and cylin- 
ders, to a room maintained at 25 deg F; and the remaining 16 companion slabs and cy- 
linders remained in the casting room at 40 deg F. At the same time, specimens were 
covered with two thicknesses of damp burlap (not in contact with surface) and a tarpaulin. 
The molds were stripped the following day and moist curing continued in the 73 deg F 
and 40 deg F rooms. In the 25 deg F room, specimens were covered with two thick- 
nesses of damp burlap which froze and prevented the specimens from drying out. 

For each storage temperature, two companion slabs and cylinders were removed for 
scale and strength tests at different ages: three ages for the 73 deg F specimens, 
eight ages for the 40 deg F specimens, and five ages for the 25 deg F specimens. 
These curing periods varied with cement type, temperature of curing, and the pres- 
ence or absence of an accelerator. Tables 7-11, presenting the strength and scale re- 
sistance data, indicate the specific lengths of curing before strength tests were made 
or the scale resistance cycles started. 

Test Methods 

Concrete cylinders were tested for compressive strength in accordance with current 
ASTM standards. A proprietary sulfur -containing capping compound was used to cap 
the top end of the cylinder. The cylinders stored at 25 deg F were thawed in the 73 deg 
F moist room for one hour prior to testing. The temperature at the center of the cylin- 
der was about 45 deg F at the end of the thaw period. 

The slabs were tested for resistance to surface scaling by alternately freezing a 
layer of water on the top surface and thawing the ice while a de-icer was distributed 
over the surface of the ice. The thaw period was limited to the amount of time re- 
quired to raise the temperature of the concrete (% in. below the top surface) to 35 deg 
F. This procedure kept further hydration to a minimum during the course of the test. 

The amount of water frozen on the slab was 250 ml. The freezing was accomplished 
in a room maintained at -20 deg F. Thawing took place in a room at approximately 73 
deg F. Upon removal from the cold room, commercial flake calcium chloride was used 
as the de-icer in the amount of 2. 4 lb per sq yd of surface area, the maximum amount 
applied in practice. At the end of the thaw period, the solution was flushed off the sur- 
face and was replaced by 250 ml of fresh water for the freeze portion of the cycle. The 
slabs were in the freezer room for approximately 20 hours and in the thaw room ap- 
proximately 4 hours. 

At intervals during the scaling test, the surfaces were examined, rated as to extent 
and depth of scale and assigned a numerical rating as follows: 

- no scaling 3 - moderate scaling 

1 - very slight scaling 4 - moderate to bad scaling 

2 - slight to moderate scaling 5 - severe scaling 

In addition to the visual ratings, photographs of the surfaces were taken periodically 
to provide a record of the amount and rate of development of scaling. 

DISCUSSION OF RESULTS 

This series of laboratory tests was conducted in order to secure information which 
would be of value in determining the minimum amount of curing required before per- 
mitting the use of de-icers on air-entrained concrete pavements. Non-air-entrained 
concretes were included for an over-all comparison with the air-entrained concretes. 

In reviewing the results of these tests, two factors are believed to be of considerable 
significance. These are the continuous moist curing of the concretes prior to test and 



27 



Non- Air - Entrained 



i 



/ 



zo 



Ty pe I Cement 
No CaCl ? 

Curing Tem perature 

tfayj curtng 



-73°R 



s' 



4 a. '• o^tf JO days 

to 



40°F 



4 



E 2 



3 



0) 

a 

V 

u 

I/) 



I 



o 



*- 



5 and SO 



tO 
4Q 



25V 



.* ^ 



D 
I/) 



i 



2 



^g pe I Cement 
BfcJClSli 

nprrd e 



' 



2 i 



mt /ana ^\ 


A 


k __ 


4 


■■■*■■ 1 


■ if ' I 








• 


Ml I * 










J Jo i 






40"f 




.rf*" - - * 










"ff ^ / 










W-j / 










lr 'off 










// r 4 * 






2 5V 


• 


i i JO 




* 




* 



50 



100 



i50 



:<v 



250 



Number of Cycles 



Air - Entra ined 



Ty pe I Ce ment ♦ A t 4 ^<ot 
No CaC l f 

Curing Temperature-7? 





Number of Cycles 



Figure 1. Effect of duration and temperature of curing on the scale 
resistance on concretes made with Type I cement - Lot 18868 



28 



Non- Air- Entrained 



Air- Entrained 




Ty pe H Cement 
No CaCI? 



Curin g Temperature -73 F 

Z6 days curing 



CD 

C 



CO 

U 

CO 

U 
(0 




JO o/i</ 40 



40° F 



25*F 






Ty pe IT Cement 
2%_CaCl 2 
Curing Temperature -73"R 




50 100 150 200 

Number of Cycles 



I day cun'ng *p 



Tu pe II Cement + A /& A gent 

No caci 7 




Curin g Temperature -1 3°F 



40° F. 



60 



^g^T ?Q, Jg^"" ^<?^ ^ ZO. JO. 4C orra 30 



8 





Ty pe II Cement + V^ Agent 
?% CaCI ? 

Curin g Temperature -73 F. 



t day curing 




?a 



40° F 



/^ 



/£ 



25°F 



JZ i GO 



50 100 150 200 

Number of Cycles 



zso 



Figure 2. Effect of duration and temperature of curing on the scale 
resistance of concretes made with Type II cement - Lot 18914. 



1 



29 



Nop- Air-Entrained 



Air-Entrained 



en 

c 



(0 

«3 
O 

ifi 
U 

(0 



3 

00 




?<3 days curing 



Tu pe III 
No CaCl ? 

Curin g Temp.73°F 




40° F 




25°F. 



50 



100 



150 




Number of Cycles 



Number of Cycles 



Figure 3- Effect of duration and temperature of curing on the scale 
resistance of concretes made with Type III cement - Lot 18893. 

the termination of the thaw portion of each cycle when the concrete surface temperature 
reached approximately 35 deg F. The continuous moist curing prevented drying of the 
concretes prior to testing. All concrete pavements undergo some drying, even during 
their early life. This drying in almost all cases increases the resistance to surface 
scaling. Terminating the thaw portion of the cycle at 35 deg F tends to keep further 
hydration at a minimum during the test and represents a severe exposure from the 
standpoint of continued hydration or curing. 

Another important factor is that these tests were made with one combination of a 
fine and coarse aggregate, both having good service records. The use of a poor aggre- 
gate in a study of this type would not be warranted since curing would not overcome the 
deficiencies of a poor aggregate. 

Scale Resistance of Non-Air-Entrained Concretes 

Detailed data on the scale resistance of the different non-air- entrained concretes 
are presented in Tables 7-11 and Figures 1-3. The number of cycles required to pro- 
duce severe scaling (a scale rating of 5) ranged from 5 to 83. These data indicate 
clearly that none of the non-air-entrained concretes showed a satisfactory degree of re- 
sistance to surface scaling — regardless of temperature, amount of prior curing, type 
of cement, or the use of an accelerator. 

Scale Resistance of Air-Entrained Concretes 



Tables 7-11 and Figures 1-3 show the same detailed information for the air-en- 



30 



trained concretes. The data indicate that some minimum amount ot prior curing is N- 
ou'red for air-entrained concrete to insure a high degree of resistance to surface scal- 
me A so it is apparent that these minimum amounts of uring are not alike in all 

MS but' depend on the type lent the temperature of curing and the presence 

of an accelerator. It appears that Increasing the rate of hydration by (MM -an or an- 
other results . a s. er required minimum penod of curing; in other * ds the In- 
mumcunng iod migi bee. idered a t ar, ,lar degree of hydration, by what- 

ever manner it is attained. 

The selection of the required minima, raring periods for these different air-en- 
traine concretes ir ■ the question as I I what performance in a laboratory scaling 

est is equivalent to excellent performance under various field conditio f exposur. 
For these test >e n imum required curing pi >l iod w- defined th. n in mum 
lenr f time nec« I - reduce the scale rating to 1 ( very slight s< Ling ) at 100 

es of test. E ended laboratory experience as shown that 100 cycles of Has t 
dure no more than < slight scaling normally Indicate ex nt resist* 

Jo ding under field condit. s. Sim I the numi i r of CfClSI • produ. I evere 

scaling ranged from 5 to 83 for trie non-air- <nt ran oncr< »t nppeftri I I the 

criterion • 1 for . ilmum curing period is • c« itire on* 

>U( »g List thai nimun squired curing p< i for adequate I 

n as* : :ures 1-3 fftcilttftfc ese sell 

P * { "' Mn >ium Curing I I kod - days 

(at ,r) at 73 deg F at 40 deg F at 25 deg F 

I 7 15 6 °-» 
2 7 7 >0 

U 7 12 35 

2 7 7 28 






7 7 24 



A l aeent added at si als 5 * ' /< a»r. 



It . 






irt' ) itoraci 



• • • 



v. t 



u 



i mphaeUii ' lm ^ ,: '' '' P* ra,ure 

n. - i II. the um f an ftcceiei as benefi- 



»g t. ipe res, but was eoefl< lal at 73 deg 

d 40 deg Y temperatures, it ll < ■ ' 'hat 






OfU 

riKpe 



r 



»e ; enti aed la ncretes are appi ely the same 



normai ed by ■ ay depa to insu .ate dev« pri 

p* raJ.' I nese laborat , t. ind d* that an • ntralnee 

is mperatures of 40 alr< mc • if- 

■ slstance SfttodSV* adequate le fi *ae 

ng t* ds b« ised somewhat ... r ' 1 

In spe ases, a justified i llo* I *. infl^ 






«-m « s on field on He. 

a developed by these coocretes at the m *ng P* 

N f, » n ir th. Ul U on the following pSfft. At 73 BSg V and 40 deg f th, BtreftglM rang«- 

> 4500 psi tin ageb f|g3740phi )t appeart irot 

p- iod prit pern < jse ' di ■ was ind ed by the development of s 

tnprest • t ength lev* I about 4000 psi. 

SUMMAl ONCLUSJ' m 

These Lab atory tests ht% dsd a basis Cor m of m sum re- 

quired on ; r tor • use of < a. «SB as 

a de rhe mois ndu e specimen ar, the nsnner of testing a « such 

iat ens ree« d be or I conservai da. -semes the 

use of a <i aggregates mum air contest ' the torn x 



31 



Cement 
Type a 


Percent 

CaCU 
(accelerator) 


Co 

I 

at 73 deg 


mpressive Strength 
Minimum Curing Pe: 
F at 40 deg F 

3900 
3700 


- psi 
riod 




at 25 deg F 


I 



2 



2 


3800 
4100 

3250 
4500 


(1010)° 
2300 


II 




3400 
3300 


880 
3200 


III 





3700 




3750 


3050 



a A/E agent added at mixer to entrain 5 t l / 2 % air. 

b Figure in parentheses is strength developed at maximum period 

of curing. These concretes showed poor resistance to scaling. 

The following statements appear valid: 

1. Non-air-entrained concrete has little resistance to surface scaling resulting from 
the use of de-icers. Increased amounts of curing up to 60 days raised the level of re- 
sistance, but the highest level attained by these non-air-entrained concretes is unsatis- 
factory. 

2. Air-entrained concrete has a high resistance to surface scaling resulting from 
the use of calcium chloride as a de-icer. However, adequate curing is required before 
calcium chloride may safely be used. This should apply also to the use of other de- 
icing materials. 

3. At temperatures above freezing (specifically at 40 deg F and 73 deg F) the amount 
of curing required for the air-entrained laboratory concretes is little more than is ne- 
cessary to develop a level of strength sufficient to carry traffic loads. These curing 
periods were 7 days at 73 deg F and 7 to 15 days at 40 deg F. These periods should be 
increased by a factor of 3 for actual field practice. 

4. The periods of curing for these air-entrained concretes were approximately the 
same for Type I and II cements, both with and without an accelerator, for temperatures 
of 40 deg F and 73 deg F. For Type III cement without an accelerator, the curing per- 
iod at 73 deg F was the same as for the Type I and n cements, but at 40 deg F the re- 
quired curing period was less. 

5. For these air-entrained concretes, the use of calcium chloride as an accelerator 
resulted in shorter minimum curing periods at temperatures of 40 deg F and 25 deg F. 

6. A curing temperature below freezing (25 deg F) resulted in excessively long cur- 
ing periods. In some cases where adequate scale resistance was obtained, the concrete 
is unacceptable because of low strength. 

7. The development of a certain level of strength has merit as an index to the a- 
mount of curing required for air-entrained concrete prior to permitting the use of de- 
icers. 

REFERENCES 

1. Hansen, W. C. , "Effect of Age of Concrete on Its Resistance to Scaling Caused 
by Using Calcium Chloride for Ice Removal," ACI Proc Vol 50, p. 341, January, 1954. 

2. Klieger, Paul, "The Effect of Entrained Air on Strength and Durability of Con- 
cretes Made with Various Maximum Sizes of Aggregate," Highway Research Board 
Proceedings, 31st Annual Meeting, 1952, p. 177. 

HRB:OF-63